Reversible rolling-mill and process for the manufacture of weldless tubes and other hollow bodies



. E. DEFERT. REVERSIBLE ROLLING MILL AND PROCESS FOR THE MANUFACTURE OF WELDLESS TUBES AND OTHER HOLLOW BODIES.

APPLICATION FILED MAR. o, I915.

1,361,025. Patented Dec. 7, 1920.

2 SHEETS-SHEET I.

' Fig .1

. .Tnven for A ttotne y E. DEFERT.

REVERSIBLE ROLLING MILL AND PROCESS FOR'ITHE MANUFACTURE OF WELDLESS TUBES-AND OTHER HOLLOW BODIES.

APP LICATION FILED MAR. a. 1918.

Patented Dec. 7, 1920.-

UNITED STATES PATENT OFFICE.

ERNEST DEFEBT; OF ST.'-CHA MOND, FRANCE.

REVERSIBLE ROLLING-MILL AND' PROCESS FOR THE MANUFACTURE OF WELDLESS TUBES AND OTHER HOLLOW BODIES.

Specification of Letters Patent. P t t 7, 1 2

Application filed March 6, 1918. Serial No. 220,815.

T 0 all whom it may concern:

Be it known that I ERNEST DEFERT, a citizen of the French Iiepublic, residing at Saint-Chamond, Loire, 13 Avenue de la Gore, France, have invented certain newand useful Improvements in Reversible Rolling-Mills and Processes for the 'Manufacture of Weldless Tubes and other Hollow Bodies; of which the following is a specification.

Weldless tubes and other hollow bodies have alreadv been produced-by rolling by means of rolling mills working on the ger rolling process.

The characteristic feature of pilger rolling mills consists in the rolling out of the successive portions of the billet in such a manner that the thickness of each bite is reduced to the final thickness of the finished tube before the next bites are en-i gaged by the rolls. In the known pilger rolling mills the direction of. rotation of the rolls is constant; the rolling of the billet takes place only during half of a revolution of the rolls during which the billet and the mandrel are forced back. During the next following half revolution the billet and the mandrel are returned into their initial positions by a tension device.

That process is quite suitable for rolling tubes, but it has great difiiculties due to the direct driving by fiy-wheel which is the usual drive employed in ordinary rolling mills of that type.

The present invention consists in improvements in rolling mills for rolling weldless tubes and other weldless hollow bodies by means of rolls analogous to those of pilger rolling mills.

The invention has also for its object to provide an improved process for the manufacture of weldless tubes and hollow bodies.

The improvements'of the present invention in rolling mills consist substantially in a peculiar a paratus for driving the rolls by means 0? these devices having the eifect of imparting an oscillatory motion to the rolls and afiording a certain number of important advantages hereinafter stated. I

The accompanying drawings illustrate diagrammatically 'by way of example an embodiment of the improved apparatus forming the subject matter of the present invention.

pil- 3 pinions and a double rack,-

In these drawings ion housing.

I Fig. 2 is a plan of an element of a rolling mill illustrating the relation between the roll housing and the pinion housing.

Fig. 3 is a sectional side elevation of the roller housing showing the billet in the bite of the rollers.

Fig. 4 is a similar view as Fig. 3 but illustrating the billet in the cavity. provided in the rolling groove. I

As shown, the pinion housing 1 comprises substantially a pair of pinions 2, 2', between which a double rack 3 is adapted to pass 'which engages with the two pinions and has avaried alternating rectilinear motion. Through these pinions 2, 2', and shafts 4, the said motion is transmitted to the rolls 5 mounted in the housing 6. The rolls 5 thus receive an oscillatory motion alternately in each direction.

The operation of the improved rolling mill is as follows The reciprocating motion of the double rack 3 is produced by any suitable device such as for example by means of an hydraulic press. This motion is transmitted to the rolls 5 by the intermediary of the pinions 2 and 2' which are 'mounted on the couplin shafts 4 and engage with .said rack. Consequently. instead of the direction of rotation of the operating rolls being constant, such as is the case in pilger rolling mills, an oscillating movement is imparted to the rolls. Fig. 3 shows the billet in bite of the rolls during their oscillating motion. The rolls 7 shown in section,

illustrate the design of the operative rolling.

The billet has just been released by the op- I erative part of the rollers and is in the cavity. In this position the mandrel with the billet execute a rotary movement of 90 and is then ready to be again engaged by.

the rollers when the latter'are moving 1n the direction indicated by the arrows, whereby a new portion 8 of-the billet will be rolled. It will be readily understood that in this manner the return movement of the billet to its original position is effected by the rolls 5 themselves, that the rolling takes place in both directions of the reciprocating motion of the billet and thereby rendering the rolling almost continuous. This is one of the essential characteristic features of the present invention.

The speed of rolling is variable and the speed of the billet and the mandrel is at every instant a function of the speed of the rack 3. The movements of the said rack are produced according to a law of sines or an analogous law by means of a hydraulic press for instance; the speed of the masses in motion being almost nil in the neighborhood of the 'ends of the pass atthe instant when the billet is leading the rolling groove. The billet thus remains in position and can make aquarter of a revolution on its own axis while awaiting to be reengaged by the rolls for the next. pass.

This invention is not limited to the particular construction of the driving apparatus hereinbefore described, since this ap parsitus may be modified in various ways without departing from the nature of the invention.

The improved apparatus of this invention for driving the rolls has the following main advantages:

(a) It allows of dispensing with the tension and brake devices employed in pilger rolling mills; I

. (b) The useful length of the rolling groove, and consequently the length of ,tube which is rolled in each ass, may be increased in a considerable egree;

(a) Rolling can be effected in both directions and consequently the rolling is rendered almost continuous;

(d) The similarity between the movements of the driving member and of the billet facilitates the regulation and operationof the rolling mill;

(e) The improved device simplifies the machinery actuating the rolling mill.

The use of the improved apparatus allows also of extending the employment of rolling mills of this kind to the production of-forgings, and more particularl to the forging at a suitable temperature 0 special steels or of thin workpieces that cool rapidly; in fact the rolling of the ordinary tubes of commerce is merelya particular case of use of ordinary pilger rolling mills.

What I claim is 1. A process for the manufacture of weldless tubes and hollow bodies, consisting in driving the rolls by means of a pair of pinions, transmitting said movement to the rolls, reciprocating the billet by the action of said rolls, rolling the billet in both directions of its movement, and subjecting the mandrel with the billet to a rotary movement of 90 at the end of each operative pass when in the cavity provided in the rolling groove of the said rolls.

2. In a rolling mill, more particularly applicable for hot-rolling weldless tubes and other hollow articles, an apparatus for driving the 'rolls, comprising a pair of pinions, double racks having an alternating rectilinear motion, for actuating said pinions, and means for transmitting the resulting motion of said pinions to the rolls, whereby the latter receive an alternating oscillatory motioh which renders the rolling operation practically continuous.

In testimony whereof I have signed my name to this specification.

ERNEST DEFERT.

Witnesses MARIN GAGHON, GRADY CORBITT. 

